After Union Hardware stopped making Tower's, a Mr. Hugo Foth continued making them and they were unmarked. This is from information in Manacles of the World, by Tom Gross (A great book).
There is a picture in the gallery of this Forum showing the single link with swivels and the box marked Foth Lock Co.
I just got a pair of unmarked Tower double locks, not with the single link but with the three round (center one curved) and no swivels.
It seems that Foth would be using only the single link/swivel configuration used by Union at that time. I think there was an imitation Tower that was unmarked, but the key hole was rotated as I remember.
Does anyone have a unmarked "Tower" with just the three links? Did Foth make both configurations of the cuff?